The invention relates to tools for manual sanding and more particularly to sanding devices provided with a vacuum connection for drawing off the dust created by the sanding action.
The sanding of wood or plaster is typically accomplished using a sanding block which is hand-held and to which sheets of sand paper can be removably attached. The dust generated by the sanding action falls freely in the work area and therefore requires subsequent cleanup.
Various devices have been designed to provide a vacuum connection to the sander head to pick up the dust generated by the sanding action in the vicinity of the sander head. For example, U.S. Pat. No. 4,062,152, issued Dec. 13, 1977 to Mehrer discloses a sander which is connected to a vacuum source by a hollow tubular handle. A porous abrasive sheet is mounted on the front surface of a backing plate which has a number of bores which provide an air passageway from the abrasive sheet to a manifold which in turn communicates with the tubular handle by a hollow sleeve universally mounted on the sander body. This device is suited for use on the end of a long handle, but not for holding in the user's hand. Further, the design of the backing plate is not conducive to picking up dust around the edges of the sander, and the vacuum is lost when one end of the device is lifted.
Another vacuum sanding device is disclosed in U.S. Pat. No. 4,184,291, issued Jan. 22, 1980 to Marton. Marton discloses a sander with a circular backup pad having a number of apertures. The sanding disc has matching apertures. A relief valve is provided to allow the worker to release the suction from the sanding pad. However again the arrangement of apertures in the backing pad is such that dust generated near the edges of the pad is not picked up. The shape of this sander is also not well adapted for reaching corners, as is necessary in most home renovation situations.
U.S. Pat. No. 4,680,895 issued Jul. 21, 1987 to Roestenberg discloses a rectangular hand-held vacuum sanding block in which the vacuum suction is provided along either vertical edge of the device, with skirts being provided to direct the suction along either edge. This design is not effective to sand into a corner, and the suction does not assist in holding the sander to the wall.
Finally, in a more recent Marton U.S. Pat. No. 4,616,449 issued Oct. 14, 1986, the problem of gathering dust around the periphery of the sanding device is addressed. Again, the proposed solution is the provision of a peripheral opening formed between a chamfered edge of the base and a peripheral rim. Such an arrangement is still not completely effective to pick up dust around the edges of the sanding surface.
Other prior art sanding devices are shown in Shaw U.S. Pat. No. 4,759,155 and Reiter U.S. Pat. No. 4,779,385. Such devices provide a vacuum chamber behind the support pad which adds to the cost of manufacture and reduces the effectiveness of the vacuum suction around the periphery of the pad.